Fidelity sound systems, whether in a residential living room or a theatrical venue, approximate an actual original sound field by employing stereophonic techniques. These systems use at least two presentation channels (e.g., left and right channels, surround sound 5.1, 6.1, or 11.1, or the like), typically projected by a symmetrical arrangement of loudspeakers. For example, as shown in FIG. 1, a conventional surround sound 5.1 system 100 includes: (1) front left speaker 102, (2) front right speaker 104, (3) front center speaker 106 (center channel), (4) low frequency speaker 108 (e.g., subwoofer), (5) back left speaker 110 (e.g., left surround), and (6) back right speaker 112 (e.g., right surround). In system 100, front center speaker 106, or a single center channel, carries all dialog and other audio associated with on-screen images.
However, these systems suffer from imperfections, especially in localizing sounds in some directions, and often require a fixed single listener position for best performance (e.g., sweet spot 114, a focal point between loudspeakers where an individual hears an audio mix as intended by the mixer). Many efforts for improvement to date involve increases in the number of presentation channels. Mixing a larger number of channels incurs larger time and cost penalties on content producers, and yet the resulting perception fails to localize sound in proximity to a visual cue of sound origin. In other words, reproduced sounds from these sound systems are not perceived to emanate from a video on-screen plane, and thus fall short of true realism.
From the above, it is appreciated by the inventors that techniques for localized perceptual audio associated with a video image is desirable for an improved natural hearing experience.
The approaches described in this section are approaches that could be pursued, but not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated, it should not be assumed that any of the approaches described in this section qualify as prior art merely by virtue of their inclusion in this section. Similarly, issues identified with respect to one or more approaches should not assume to have been recognized in any prior art on the basis of this section, unless otherwise indicated.